M. Leboyer et al., Decreased serotonin transporter binding in unaffected relatives of manic depressive patients, BIOL PSYCHI, 46(12), 1999, pp. 1703-1706
Background: There are numerous reports of decreased binding to platelet ser
otonin transporter (5-HTT) in depression, suggesting that it might be consi
dered a trait marker of depression. To further investigate whether reduced
5-HTT function could be an endophenotype in manic depressive illness, we lo
oked for abnormalities of platelet 5-HTT among subjects who are potential c
arriers of genetic vulnerability to manic depressive illness (MDI).
Methods: Blood samples were obtained from 20 unaffected relatives from fami
lies with at least two individuals with bipolar disorder and from 19 contro
l participants. Plasma 5-HIAA, platelet 5-HT, and [H-3] imipramine binding
were measured
Results: Unaffected relatives manifested lower platelet 5-HTT function than
control participants as revealed both by reduced number and diminished aff
inity of imipramine binding sites and diminished platelet 5-HT content.
Conclusions: These preliminary results suggest that reduced 5-HTT function
could be considered a trait marker or an endophenotype in MDI. Biol Psychia
try 1999;46: 1703-1706 (C) 1999 Society of Biological Psychiatry.